Gauge control rolling mills and methods of rolling



y 9, 1968 T. A. FOX 3,391,557

GAUGE CONTROL ROLLING MILLS AND METHODS OF ROLLING Filed Nov. 12, 1964Fig .2.

Fig.4.

INVENTOR Z Thomas A. Fox

United States Patent 01 hoe 339L557 Patented July 9, I968 3,391,557GAUGE (JON'IROL ROLLING MILLS AND METHODS 01*" EQLLING Thomas A. Fox,Youngstown, Ohio, assignor to Fox Industries, Inc. Filed Nov. 12, 1964,Ser. No. 410,466 8 Claims. (Cl. 72-16) This invention relates to gaugecontrol rolling mills and methods of rolling and particularly to arolling mill prestressed to a level producing a given reduction onnormal entering strip and means varying the mill stress as the stripthickness deviates from the average or norm to produce a final uniformgauge strip.

The problem of producing a metal strip of uniform gauge is one that haslong plagued the metal working industry. Various attempts have been madeto control the gauge of strip but with less than satisfactory results.The problem arises because of the fact that the stock entering therolling mill is itself not uniform. Accordingly, a

mill set to produce a given reduction will produce strip which has beensubstantially uniformly reduced but which is not of uniform gauge. Forexample, a mill which is set to provide a reduction of 0.005 inch willnot discriminate between thick and thin areas on the entering strip butwill produce an average of 0.005 inch reduction on all parts of thestrip. The resulting finished strip will accordingly be reduced 0.005inch but will still have thick and thin areas. The problem is to providea mill and method of rolling which will reduce the thick portions agreater amount and the thin portions a lesser amount than the norm.

I have developed a mill and method of rolling which will accomplish thisideal of reducing thick areas a proper proportion more than the norm andthe thinner areas a lesser amount to produce a strip of extraordinaryuniformity.

Preferably, I provide work rolls on opposite sides of a strip passlineadapted to receive a strip to be reduced therebetween, journals at theends of said work rolls, a housing carrying said joumals, means in saidhousing adapted to load said housing and roll journals to an initialload equivalent to a preselected reduction on the average thickness of astrip entering the mill, means for varying said load on the housings andjournals when the strip thickness changes from said average thicknessand means for measuring strip thickness controlling the means forvarying the load to increase the load as the strip thickness increasesand decrease the load as the strip thickness decreases. The loading onthe housings is preferably accomplished by hydraulic cylinders and maybe controlled by known commercial servo mechanisms such as thosemanufactured by Vickers Company, in turn controlled by the amplifiedsignal from a conventional strip thickness gauge such as the Pratt andWhitney X-ray or beta ray gauges.

In the practice of the method of this invention, a mill housing withwork rolls is preloaded to a level representing a preselected reductionon the average thickness of the entering strip. The preload is varied upor down depending upon increases or decreases in entering stripthickness. For example, assuming that a preload of 500,000 poundsrepresents a reduction of 0.005 inch in a given strip, a decrease in thepreload to zero would mean no reduction and an increase of preload to1,000,000 pounds would mean a reduction of 0.010 inch.

In the foregoing general description I have set out certain objects,purposes and advantages of my invention. Other objects, purposes andadvantages of my invention will be apparent from a consideration of thefollowing description and the accompanying drawings in which FIGURE 1 isa side elevation of a mill incorporating my invention showing aschematic control system;

FIGURE 2 is a section on the line 11-11 of FIGURE 1;

FIGURE 3 is a side elevation of a mill embodying a second embodiment ofmy invention;

FIGURE 4 is a side elevation of a mill embodying a third embodiment ofmy invention;

FIGURE 5 is a side elevation of a mill embodying a fourth embodiment ofmy invention; and

FIGURE 6 is a side elevation of a mill embodying a fifth embodiment ofmy invention.

Referring to the drawings, I have illustrated a housing 10 having awindow 11 carrying an upper back up roll chock 12 and a lower back uproll chock 13 with back up rolls 14 and 15 respectively journaledtherein. The upper back up roll chock 12 is provided with a recess 16carrying an upper work roll chock 17. The lower back up roll chock 13 isprovided with a like recess 18 having a work roll chock 19 therein. Aconventional screw-down 20 is provided to urge the back up roll chocks12 and 13 toward each other. Hydraulic cylinders 21 and 22 are placedbetween the back up roll chocks to exert a prestress load on the housing11. Preferably, the initial stress for a reduction of 0.005 inch isabout 500,000 pounds. A strip 23 entering the nip of the work rollspasses between a conventional B-ray gauge head 24 such as thatmanufactured by Pratt and Whitney which transmits a thicknessmeasurement through a conventional amplifier 25 to a conventional servovalve 26 between a source of hydraulic fluid 27 under pressure and thecylinders 21 and 22. When a thin spot appears on the strip, the pressureon cylinders 21 and 22 is reduced in proportion to the relationshipbetween the actual reduction required and the set average. For example,if the average reduction is 0.005 inch and the prestress pressure is500,000 pounds and an area is noted which is 0.002 inch under theaverage strip thickness, the prestress is reduced to 300,000 pounds sothat the reduction is 0.002 inch less than average. On the other hand,if the area is thicker than average, the pressure on cylinders 21 and 22is increased and the reduction is correspondingly greater.

In FIGURES 3 through 6, I have illustrated other embodiments in whichthe prestress cylinders are located in different positions andcombinations. For example, in FIGURE 3 I have placed prestress cylindersand 41 between the back up roll chocks and cylinders 43 and 44 betweenthe top back up roll chock and the top of the window in the housing. InFIGURE 4 I have placed the prestress cylinders 45 and 46 between the topback up roll chock and the top of the window in the roll housing. InFIGURE 5 I have placed prestress cylinders 47 and 48 between the back uproll chocks and have incorporated the roll bending cylinders of myPatent 3,024,679 to control the strip contour. In FIGURE 6 I haveillustrated an hour glass form of roll housing in which the Work rollchocks 50- and 51 are held between shoulders 52 and 53 projectinginwardly from the sides of the window 54 of the roll housing 55.Prestress cylinders 56 and 57 are mounted in the shoulders 52 and 53 tobear against the bottom back up roll chock 58. I also provide work rollbending cylinders 5960 and 6162 as described in my Patent 3,024,679. Inall of the forms illustrated in FIGURES 3 through 6, a conventionalthickness gauge and servo valve are used to control the prestresspressure as described in connection with FIGURES 1 and 2.

While I have illustrated and described certain preferred embodiments andpractices of my invention in the foregoing specification, it will beunderstood that this invention may be otherwise embodied within thescope of the following claims.

I claim:

1. A rolling mill structure comprising work rolls on opposite sides of astrip passline receiving a strip to be reduced therebetween, journals atthe ends of said work rolls, a housing carrying said journals, a firstload means in said housing urging the work rolls together and adapted toload said housing and roll journals to a preselected constant load, avariable load means in said housing adapted to act in opposition to saidfirst load means to load said housing and roll journals to an initialload equivalent to a preselected reduction on the average thickness of astrip entering the mill, means for varying said variable load on thehousings and journals when the strip thickness changes from said averagethickness and means for measuring strip thickness controlling the loadvarying means to increase the load as the strip thickness increasesabove said average and decrease the load as the strip thicknessdecreases below said average.

2. A rolling mill structure comprising work rolls on opposite sides of astrip passline receiving a strip to be reduced therebetween, journals atthe ends of said work rolls, a housing carrying said journals, a firstload means in said housing urging the work rolls together and adapted toload said housing and roll journals to a preselected constant load, avariable load means in said housing adapted to act in opposition to saidfirst load means to load said housing and roll journals to an initialload equivalent to a preselected reduction on the average thickness of astrip entering the mill, means for varying said variable load on thehousings and journals when the strip thickness changes from said averagethickness and means preceding the work rolls adjacent the strip passlinefor measuring strip thickness controlling the load varying means toincrease the load as the strip thickness increases above said averageand decrease the load as the strip thickness decreases below saidaverage.

3'. A rolling mill structure comprising back up rolls on opposite sidesof the strip passline, work rolls between said back up rolls receiving astrip to be reduced therebetween, journals at the ends of each of saidback up rolls and said work rolls, a housing carrying said journals, afirst load means in said housing urging the work rolls together andadapted to load said housing and roll journals to a preselected constantload, a variable load means in said housing adapted to act in oppositionto said first load means to load said housing and roll journals to aninitial load equivalent to a preselected reduction on the averagethickness of a strip entering the mill, means for varying said variableload on the housings and journals when the strip thickness changes fromsaid average thickness and means preceding the work rolls adjacent thestrip passline for measuring strip thickness controlling the loadvarying means to increase the load as the strip thickness increasesabove said aver-age and decreases the load as the strip thicknessdecreases below said average.

4. A rolling mill structure comprising work rolls on opposite sides of astrip passline receiving a strip to be reduced therebetween, journals atthe ends of said work rolls, a housing carrying said journals, a firstload means in said housing urging the work rolls together and adapted toload said housing and roll journals to a preselected constant load, avariable hydraulic load means in said housing adapted to act inopposition to said first load means to load said housing and rolljournals to an initial load equivalent to a preselected reduction on theaverage thickness of a strip entering the mill, means for varying saidvariable load on the housings and journals when the strip thicknesschanges from said average thickness and means for measuring stripthickness controlling the load varying means to increase the load as thestrip thickness increases above said average and decrease the load asthe strip thickness decreases below said average.

5. A rolling mill structure as claimed in claim 4 wherein the means forvarying the load on the housing is a servo controlled valve and themeans for measuring strip thickness controls the opening and closing ofsaid servo valve.

6. The method of rolling a strip to uniform thickness comprising thesteps of:

(l) feeding a strip to be rolled to the work rolls of a rolling mill inwhich the work rolls are journaled in a mill housing;

(2) preloading the mill housing and the roll journals thereon with afirst preselected constant load and with a variable load in oppositionto the first load to provide an initial load equivalent to a preselectedreduction on the average thickness of said strip;

(3) continuously measuring the thickness of the strip ahead of the workrolls; and

(4) varying the variable preload on the mill housing and roll journalsto increase the load as the strip thickness increases above said averageand decrease the load as the strip thickness decreases below saidaverage.

7. A rolling mill structure as claimed in claim 3 wherein pressure meansis provided at the ends of each work roll acting on and moving thejournals of said work rolls transversely to the strip passline to causethe ends of said work rolls to move toward each other so as to cause themiddle thereof to engage a strip being rolled as a fulcrum to provide adesired strip contour from edge to edge of said strip.

8. A rolling mill structure as claimed in claim 7 wherein the pressuremeans are hydraulic cylinders between each work roll journal and itsadjacent back up roll journal.

References Cited UNITED STATES PATENTS 672,466 4/1901 Smith 72162,523,553 9/ 1950 Blain 72-16 3,024,679 3/1962 Fox 72-243 3,197,9868/1965 Freedman et al. 72-l6 X FRANCIS S. HUSAR, Primary Examiner.

HARRISON L. HINSON, Examiner.

1. A ROLLING MILL STRUCTURE COMPRISING WORK ROLLS ON OPPOSITE SIDES OF ASTRIP PASSLINE RECEIVING A STRIP TO BE REDUCED THEREBETWEEN, JOURNALS ATTHE ENDS OF SAID WORK ROLLS, A HOUSING CARRYING SAID JOURNALS, A FIRSTLOAD MEANS IN SAID HOUSING URGING THE WORK ROLLS TOGETHER AND ADAPTED TOLOAD SAID HOUSING AND ROLL JOURNALS TO A PRESELECTED CONSTANT LOAD, AVARIABLE LOAD MEANS IN SAID HOUSING ADAPTED TO ACT IN OPPOSITION TO SAIDFIRST LOAD MEANS TO LOAD SAID HOUSING AND ROLL JOURNALS TO AN INITIALLOAD EQUIVALENT TO A PRESELECTED REDUCTION ON THE AVERAGE THICKNESS OF ASTRIP ENTERING THE MILL, MEANS FOR VARYING SAID VARIABLE LOAD ON THEHOUSINGS AND JOURNALS WHEN THE STRIP THICKNESS CHANGES FROM SAID AVERAGETHICKNESS AND MEANS FOR MEASURING STRIP THICKNESS CONTROLLING THE LOADVARYING MEANS TO INCREASE THE LOAD AS THE STRIP THICKNESS INCREASESABOVE SAID AVERAGE AND DECREASE THE LOAD AS THE STRIP THICKNESSDECREASES BELOW SAID AVERAGE.